The edge-lit LED backlight modules are usually used in the current existing LCD devices. Based on consideration of weight and trend of reduction of thickness, the thickness of the light guide plate is usually designed to be the same as the width of the LED. The method often used in the current design is to compress the light guide plate by the rubber frame, to achieve the aim that the light guide plate is aligned with the LED.
FIG. 1 shows the mode of positioning of the light guide plate of the currently used backlight module. Said backlight module comprises a LED 110, a LED packaging substrate 120, a light bar bracket 130, a rubber frame 200, a backplane 300 and a light guide plate 400, wherein the LED 110, the LED packaging substrate 120, the light bar bracket 130 are respectively fixed on the backplane 300; the light guide plate is arranged in the position corresponding to the LED 110; and the rubber frame 200 is a thin plate arranged outside the backlight cavity; one part of the rubber frame 200 which is in parallel with the light guide plate 400 is provided with a lug boss 210 on the side facing the light guide plate; the light guide plate 400 is compressed and fixed by the lug boss 210 so that the light guide plate is aligned with the LED 110; and the alignment here means that the light incident surface of the light guide plate 400 can completely coincide with the light emergent surface of the LED 110. However, with the process of reduction of thickness of the LCD devices, the thickness of the rubber frame 200 becomes thinner and thinner, and as a result the compressing force provided by the lug boss 210 is limited. If the rubber frame is still used for compressing the light guide plate for positioning, the positioning reliability will be reduced, and the trend of reduction of thickness will be affected.